1. Field of the Invention
This invention relates to a radiation image read-out and reproducing method for reading out an image stored on a stimulable phosphor sheet by exposing the stimulable phosphor sheet to stimulating rays which cause the stimulable phosphor sheet to emit light in proportion to the stored radiation energy and photoelectrically detecting the emitted light, and more particularly to such a method suitable for a relatively small stimulable phosphor sheet used for testing a small industrial article, X-ray test of a limited part and the like.
2. Description of the Prior Art
When certain kinds of phosphors are exposed to a radiation such as X-rays, .alpha.-rays, .beta.-rays, .gamma.-rays, cathode rays or ultraviolet rays, they store a part of the energy of the radiation. Then when the phosphor which has been exposed to the radiation is exposed to stimulating rays such as visible light, light emitted by the phosphor in proportion to the stored energy of the radiation. A phosphor exhibiting such properties is referred to as a stimulable phosphor.
A sheet provided with a layer of the stimulable phosphor is referred to as a stimulable phosphor sheet and is useful for reading out image information for various purposes.
For example, as disclosed in Japanese Unexamined Patent Publication Nos. 55(1980)-12429, and 56(1981)-11395, it has been proposed to use the stimulable phosphor sheet in a radiation image recording and reproducing system. That is, the stimulable phosphor sheet is first exposed to a radiation passing through an object such as human body to have a radiation image of the object stored thereon, and is then exposed to stimulating rays which cause the stimulable phosphor sheet to emit light in proportion to the stored radiation energy. The light emitted by the stimulable phosphor sheet upon stimulation thereof is photoelectrically detected and converted to an electric image signal by a photodetector, and the radiation image of the object is reproduced as a visible image by use of the image signal on a recording medium such as a photographic film, a display device such as a cathode ray tube (CRT), or the like.
However, in the conventional systems, the stimulating rays are caused to raster-scan the stimulable phosphor sheet in order to read out image information over a wide range on the sheet, and accordingly, complicated main scanning and sub scanning are required for stimulation of the sheet and for detection of the light emitted by the sheet upon stimulation thereof, whereby the overall system is complicated and becomes large in size.
The light emitted by the sheet and carrying image information is photoelectrically detected by a photodetector and delivered to the visible image reproducing section after converted to an electric signal. When the radiation image is reproduced as a visible image on a recording medium such as a photographic film by, for instance, a recording light beam modulated on the basis of the electric signal, complicated main scanning and sub scanning are required as in the case of stimulation of the sheet. This further makes the system large in size and complicated.
On the other hand, since the aforesaid system is very effective for medical diagnosis, there have been demands towards miniaturization and simplification of the system and reduction of the manufacturing cost of the system. If such demands can be met, not only large hospitals but also consultation rooms of medical practitioners can be equipped with the system.
In the case that the system is for handling a limited part of the human body or the like, the stimulable phosphor sheet need not be large in size, and a small stimulable phosphor sheet suffices for such purposes. Accordingly, a miniaturized and simplified system for small size stimulable phosphor sheets will be convenient.
Further, in the case where the stimulable phosphor sheet is used for non-destructive inspection of small industrial articles, autoradiography of hybrid formation of DNA colonies or of electrophoresis pattern of protein, or the like, the effective area of the sheet may be substantially small. In such cases, it will be preferred that the image read-out and reproducing system conforms to the small stimulable phosphor sheet in scale. Further along with miniaturization of the system, there is an increasing demand for simplification of operation and adjustment of the system and for reduction of the manufacturing cost.